Fluorogenic squaraine dimers for the flow cytometry detection of urinary tract infections

Rapid diagnosis of bacterial infections is essential for guiding antibiotic treatment and mitigating the global spread of antibiotic resistance. Here, we report the development of fluorogenic bacteria-specific probes for the flow cytometry detection of urinary tract infections. These probe, composed of a covalently linked pair of squaraine dyes conjugated to a bacteria-specific peptidic vector, exploits the phenomenon known as aggregation-caused quenching. The chemical structure of the squaraine dyes was finely tuned to ensure selectivity for bacteria over eukaryotic cells and serum albumin. The most effective probe enabled rapid and quantitative detection of bacteria in patient urine samples by flow cytometry within minutes. INTRODUCTION Due to the planetary spread of antibiotic resistance, bacterial infections have become one of the most critical dangers facing modern society.1–3 The number of deaths from multidrug-resistant bacteria is rising and, without new antimicrobial therapeutics, could reach 10 million deaths annually by 2050.4 Although the development of new antibacterial therapeutics and vaccines is of high priority,5 additional measures should be taken to develop fast methods for the early diagnosis of bacterial infections to reduce the misuse and the overuse of antibiotics. The standard